Expansion cards can be added to computer systems to lend additional functionality or augment capabilities. Current expansion cards interface and communicate with computer systems using primarily a multi-drop parallel bus network architecture, such as Peripheral Component Interconnect (PCI) or VERSAmodule Eurocard (VMEbus). A multi-drop parallel bus architecture has the disadvantage that it can only be used to support one instantaneous communication between modules in a computer system or network. However, some applications have requirements for simultaneous high bandwidth transfers between modules that cannot be handled by the multi-drop parallel bus architecture.
In the prior art, expansion cards, particularly mezzanine cards, are placed on payload modules mounted in chassis-type computer systems, such as VMEbus type systems known in the art. The prior art method of interfacing the expansion cards requires the payload module to manage the mezzanine cards through use of a processor and bus onboard the payload module. This adds complexity and expense when adding additional functionality to the chassis-type computer system. Therefore, it is desirable to provide expansion cards in a chassis-type environment that support high-speed data transfers, while minimizing the complexity and expense of controlling the expansion cards from the payload module.
In the prior art, 6U form factor cards are common. The 3U form factor offers an advantage for applications where physical space is at a premium. The 9U form factor offers an advantage of placing more computing features on a given card. Prior art 3U and 9U form factor expansion cards interface with a backplane using parallel multi-drop networks. This has the disadvantage of being slow and cumbersome for network expansion.
Accordingly, there is a significant need for an apparatus and method that overcomes the deficiencies of the prior art outlined above.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the drawing have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to each other. Further, where considered appropriate, reference numerals have been repeated among the Figures to indicate corresponding elements.